title: Glycogen Synthase Kinase 3 influences cell motility and chemotaxis by regulating PI3K membrane localization in Dictyostelium.
abstract: Glycogen Synthase Kinase 3 (GSK3) is a multifunctional kinase involved in diverse cellular activities such as metabolism, differentiation, and morphogenesis. Recent studies showed that GSK3 in Dictyostelium affects chemotaxis via TorC2 pathway and Daydreamer. Now we report that GSK3 affects PI3K membrane localization, of which the mechanism has remained to be fully understood in Dictyostelium. The membrane localization domain (LD) of Phosphatidylinositol-3-kinase 1 (PI3K1) is phosphorylated on serine residues in a GSK3 dependent mechanism and PI3K1-LD exhibited biased membrane localization in gsk3(-) cells compared to the wild type cells. Furthermore, multiple GSK3-phosphorylation consensus sites exist in PI3K1-LD, of which phosphomimetic substitutions restored cAMP induced transient membrane localization of PI3K1-LD in gsk3(-) cells. Serine to alanine substitution mutants of PI3K1-LD, in contrast, displayed constitutive membrane localization in wild type cells. Biochemical analysis revealed that GSK3 dependent serine phosphorylation of PI3K1-LD is constitutive during the course of cAMP stimulation. Together, these data suggest that GSK3 dependent serine phosphorylation is a prerequisite for chemoattractant cAMP induced PI3K membrane localization.
authors.affiliation: Department of Biological Sciences, Florida International University, Miami, FL, 33199, USA.
authors.forename: Tong
authors.initials: T
authors.lastname: Sun
authors.forename: Bohye
authors.initials: B
authors.lastname: Kim
authors.forename: Lou W
authors.initials: LW
authors.lastname: Kim
mesh_terms: D002462:Cell Membrane / Q000201:enzymology* / Q000235:genetics; D000242:Cyclic AMP / Q000235:genetics / Q000378:metabolism; D004023:Dictyostelium / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D055785:Gene Knockdown Techniques; D038362:Glycogen Synthase Kinase 3 / Q000235:genetics / Q000378:metabolism*; D000076225:Mechanistic Target of Rapamycin Complex 2; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation / Q000502:physiology; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism
chemical_list: D000242:Cyclic AMP; D038362:Glycogen Synthase Kinase 3; D000076225:Mechanistic Target of Rapamycin Complex 2; D046912:Multiprotein Complexes; D019869:Phosphatidylinositol 3-Kinases; D015800:Protozoan Proteins; D058570:TOR Serine-Threonine Kinases
keywords: Dictyostelium; GSK3; PI3K; chemotaxis